/*!!
 *  Canvas 2 Svg v1.0.19
 *  A low level canvas to SVG converter. Uses a mock canvas context to build an SVG document.
 *
 *  Licensed under the MIT license:
 *  http://www.opensource.org/licenses/mit-license.php
 *
 *  Author:
 *  Kerry Liu
 *
 *  Copyright (c) 2014 Gliffy Inc.
 */

 /**
  * CircuitVerse - Edited
  * Latest npm package is 1.0.16 but we need 1.0.19
  */

"use strict";

var STYLES, ctx, CanvasGradient, CanvasPattern, namedEntities;

//helper function to format a string
function format(str, args) {
    var keys = Object.keys(args), i;
    for (i=0; i<keys.length; i++) {
        str = str.replace(new RegExp("\\{" + keys[i] + "\\}", "gi"), args[keys[i]]);
    }
    return str;
}

//helper function that generates a random string
function randomString(holder) {
    var chars, randomstring, i;
    if (!holder) {
        throw new Error("cannot create a random attribute name for an undefined object");
    }
    chars = "ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    randomstring = "";
    do {
        randomstring = "";
        for (i = 0; i < 12; i++) {
            randomstring += chars[Math.floor(Math.random() * chars.length)];
        }
    } while (holder[randomstring]);
    return randomstring;
}

//helper function to map named to numbered entities
function createNamedToNumberedLookup(items, radix) {
    var i, entity, lookup = {}, base10, base16;
    items = items.split(',');
    radix = radix || 10;
    // Map from named to numbered entities.
    for (i = 0; i < items.length; i += 2) {
        entity = '&' + items[i + 1] + ';';
        base10 = parseInt(items[i], radix);
        lookup[entity] = '&#'+base10+';';
    }
    //FF and IE need to create a regex from hex values ie &nbsp; == \xa0
    lookup["\\xa0"] = '&#160;';
    return lookup;
}

//helper function to map canvas-textAlign to svg-textAnchor
function getTextAnchor(textAlign) {
    //TODO: support rtl languages
    var mapping = {"left":"start", "right":"end", "center":"middle", "start":"start", "end":"end"};
    return mapping[textAlign] || mapping.start;
}

//helper function to map canvas-textBaseline to svg-dominantBaseline
function getDominantBaseline(textBaseline) {
    //INFO: not supported in all browsers
    var mapping = {"alphabetic": "alphabetic", "hanging": "hanging", "top":"text-before-edge", "bottom":"text-after-edge", "middle":"central"};
    return mapping[textBaseline] || mapping.alphabetic;
}

// Unpack entities lookup where the numbers are in radix 32 to reduce the size
// entity mapping courtesy of tinymce
namedEntities = createNamedToNumberedLookup(
    '50,nbsp,51,iexcl,52,cent,53,pound,54,curren,55,yen,56,brvbar,57,sect,58,uml,59,copy,' +
        '5a,ordf,5b,laquo,5c,not,5d,shy,5e,reg,5f,macr,5g,deg,5h,plusmn,5i,sup2,5j,sup3,5k,acute,' +
        '5l,micro,5m,para,5n,middot,5o,cedil,5p,sup1,5q,ordm,5r,raquo,5s,frac14,5t,frac12,5u,frac34,' +
        '5v,iquest,60,Agrave,61,Aacute,62,Acirc,63,Atilde,64,Auml,65,Aring,66,AElig,67,Ccedil,' +
        '68,Egrave,69,Eacute,6a,Ecirc,6b,Euml,6c,Igrave,6d,Iacute,6e,Icirc,6f,Iuml,6g,ETH,6h,Ntilde,' +
        '6i,Ograve,6j,Oacute,6k,Ocirc,6l,Otilde,6m,Ouml,6n,times,6o,Oslash,6p,Ugrave,6q,Uacute,' +
        '6r,Ucirc,6s,Uuml,6t,Yacute,6u,THORN,6v,szlig,70,agrave,71,aacute,72,acirc,73,atilde,74,auml,' +
        '75,aring,76,aelig,77,ccedil,78,egrave,79,eacute,7a,ecirc,7b,euml,7c,igrave,7d,iacute,7e,icirc,' +
        '7f,iuml,7g,eth,7h,ntilde,7i,ograve,7j,oacute,7k,ocirc,7l,otilde,7m,ouml,7n,divide,7o,oslash,' +
        '7p,ugrave,7q,uacute,7r,ucirc,7s,uuml,7t,yacute,7u,thorn,7v,yuml,ci,fnof,sh,Alpha,si,Beta,' +
        'sj,Gamma,sk,Delta,sl,Epsilon,sm,Zeta,sn,Eta,so,Theta,sp,Iota,sq,Kappa,sr,Lambda,ss,Mu,' +
        'st,Nu,su,Xi,sv,Omicron,t0,Pi,t1,Rho,t3,Sigma,t4,Tau,t5,Upsilon,t6,Phi,t7,Chi,t8,Psi,' +
        't9,Omega,th,alpha,ti,beta,tj,gamma,tk,delta,tl,epsilon,tm,zeta,tn,eta,to,theta,tp,iota,' +
        'tq,kappa,tr,lambda,ts,mu,tt,nu,tu,xi,tv,omicron,u0,pi,u1,rho,u2,sigmaf,u3,sigma,u4,tau,' +
        'u5,upsilon,u6,phi,u7,chi,u8,psi,u9,omega,uh,thetasym,ui,upsih,um,piv,812,bull,816,hellip,' +
        '81i,prime,81j,Prime,81u,oline,824,frasl,88o,weierp,88h,image,88s,real,892,trade,89l,alefsym,' +
        '8cg,larr,8ch,uarr,8ci,rarr,8cj,darr,8ck,harr,8dl,crarr,8eg,lArr,8eh,uArr,8ei,rArr,8ej,dArr,' +
        '8ek,hArr,8g0,forall,8g2,part,8g3,exist,8g5,empty,8g7,nabla,8g8,isin,8g9,notin,8gb,ni,8gf,prod,' +
        '8gh,sum,8gi,minus,8gn,lowast,8gq,radic,8gt,prop,8gu,infin,8h0,ang,8h7,and,8h8,or,8h9,cap,8ha,cup,' +
        '8hb,int,8hk,there4,8hs,sim,8i5,cong,8i8,asymp,8j0,ne,8j1,equiv,8j4,le,8j5,ge,8k2,sub,8k3,sup,8k4,' +
        'nsub,8k6,sube,8k7,supe,8kl,oplus,8kn,otimes,8l5,perp,8m5,sdot,8o8,lceil,8o9,rceil,8oa,lfloor,8ob,' +
        'rfloor,8p9,lang,8pa,rang,9ea,loz,9j0,spades,9j3,clubs,9j5,hearts,9j6,diams,ai,OElig,aj,oelig,b0,' +
        'Scaron,b1,scaron,bo,Yuml,m6,circ,ms,tilde,802,ensp,803,emsp,809,thinsp,80c,zwnj,80d,zwj,80e,lrm,' +
        '80f,rlm,80j,ndash,80k,mdash,80o,lsquo,80p,rsquo,80q,sbquo,80s,ldquo,80t,rdquo,80u,bdquo,810,dagger,' +
        '811,Dagger,81g,permil,81p,lsaquo,81q,rsaquo,85c,euro', 32);


//Some basic mappings for attributes and default values.
STYLES = {
    "strokeStyle":{
        svgAttr : "stroke", //corresponding svg attribute
        canvas : "#000000", //canvas default
        svg : "none",       //svg default
        apply : "stroke"    //apply on stroke() or fill()
    },
    "fillStyle":{
        svgAttr : "fill",
        canvas : "#000000",
        svg : null, //svg default is black, but we need to special case this to handle canvas stroke without fill
        apply : "fill"
    },
    "lineCap":{
        svgAttr : "stroke-linecap",
        canvas : "butt",
        svg : "butt",
        apply : "stroke"
    },
    "lineJoin":{
        svgAttr : "stroke-linejoin",
        canvas : "miter",
        svg : "miter",
        apply : "stroke"
    },
    "miterLimit":{
        svgAttr : "stroke-miterlimit",
        canvas : 10,
        svg : 4,
        apply : "stroke"
    },
    "lineWidth":{
        svgAttr : "stroke-width",
        canvas : 1,
        svg : 1,
        apply : "stroke"
    },
    "globalAlpha": {
        svgAttr : "opacity",
        canvas : 1,
        svg : 1,
        apply :  "fill stroke"
    },
    "font":{
        //font converts to multiple svg attributes, there is custom logic for this
        canvas : "10px sans-serif"
    },
    "shadowColor":{
        canvas : "#000000"
    },
    "shadowOffsetX":{
        canvas : 0
    },
    "shadowOffsetY":{
        canvas : 0
    },
    "shadowBlur":{
        canvas : 0
    },
    "textAlign":{
        canvas : "start"
    },
    "textBaseline":{
        canvas : "alphabetic"
    },
    "lineDash" : {
        svgAttr : "stroke-dasharray",
        canvas : [],
        svg : null,
        apply : "stroke"
    }
};

/**
 *
 * @param gradientNode - reference to the gradient
 * @constructor
 */
CanvasGradient = function (gradientNode, ctx) {
    this.__root = gradientNode;
    this.__ctx = ctx;
};

/**
 * Adds a color stop to the gradient root
 */
CanvasGradient.prototype.addColorStop = function (offset, color) {
    var stop = this.__ctx.__createElement("stop"), regex, matches;
    stop.setAttribute("offset", offset);
    if (color.indexOf("rgba") !== -1) {
        //separate alpha value, since webkit can't handle it
        regex = /rgba\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d?\.?\d*)\s*\)/gi;
        matches = regex.exec(color);
        stop.setAttribute("stop-color", format("rgb({r},{g},{b})", {r:matches[1], g:matches[2], b:matches[3]}));
        stop.setAttribute("stop-opacity", matches[4]);
    } else {
        stop.setAttribute("stop-color", color);
    }
    this.__root.appendChild(stop);
};

CanvasPattern = function (pattern, ctx) {
    this.__root = pattern;
    this.__ctx = ctx;
};

/**
 * The mock canvas context
 * @param o - options include:
 * ctx - existing Context2D to wrap around
 * width - width of your canvas (defaults to 500)
 * height - height of your canvas (defaults to 500)
 * enableMirroring - enables canvas mirroring (get image data) (defaults to false)
 * document - the document object (defaults to the current document)
 */
ctx = function (o) {
    var defaultOptions = { width:500, height:500, enableMirroring : false}, options;

    //keep support for this way of calling C2S: new C2S(width,height)
    if (arguments.length > 1) {
        options = defaultOptions;
        options.width = arguments[0];
        options.height = arguments[1];
    } else if ( !o ) {
        options = defaultOptions;
    } else {
        options = o;
    }

    if (!(this instanceof ctx)) {
        //did someone call this without new?
        return new ctx(options);
    }

    //setup options
    this.width = options.width || defaultOptions.width;
    this.height = options.height || defaultOptions.height;
    this.enableMirroring = options.enableMirroring !== undefined ? options.enableMirroring : defaultOptions.enableMirroring;

    this.canvas = this;   ///point back to this instance!
    this.__document = options.document || document;

    // allow passing in an existing context to wrap around
    // if a context is passed in, we know a canvas already exist
    if (options.ctx) {
        this.__ctx = options.ctx;
    } else {
        this.__canvas = this.__document.createElement("canvas");
        this.__ctx = this.__canvas.getContext("2d");
    }

    this.__setDefaultStyles();
    this.__stack = [this.__getStyleState()];
    this.__groupStack = [];

    //the root svg element
    this.__root = this.__document.createElementNS("http://www.w3.org/2000/svg", "svg");
    this.__root.setAttribute("version", 1.1);
    this.__root.setAttribute("xmlns", "http://www.w3.org/2000/svg");
    this.__root.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:xlink", "http://www.w3.org/1999/xlink");
    this.__root.setAttribute("width", this.width);
    this.__root.setAttribute("height", this.height);

    //make sure we don't generate the same ids in defs
    this.__ids = {};

    //defs tag
    this.__defs = this.__document.createElementNS("http://www.w3.org/2000/svg", "defs");
    this.__root.appendChild(this.__defs);

    //also add a group child. the svg element can't use the transform attribute
    this.__currentElement = this.__document.createElementNS("http://www.w3.org/2000/svg", "g");
    this.__root.appendChild(this.__currentElement);
};


/**
 * Creates the specified svg element
 * @private
 */
ctx.prototype.__createElement = function (elementName, properties, resetFill) {
    if (typeof properties === "undefined") {
        properties = {};
    }

    var element = this.__document.createElementNS("http://www.w3.org/2000/svg", elementName),
        keys = Object.keys(properties), i, key;
    if (resetFill) {
        //if fill or stroke is not specified, the svg element should not display. By default SVG's fill is black.
        element.setAttribute("fill", "none");
        element.setAttribute("stroke", "none");
    }
    for (i=0; i<keys.length; i++) {
        key = keys[i];
        element.setAttribute(key, properties[key]);
    }
    return element;
};

/**
 * Applies default canvas styles to the context
 * @private
 */
ctx.prototype.__setDefaultStyles = function () {
    //default 2d canvas context properties see:http://www.w3.org/TR/2dcontext/
    var keys = Object.keys(STYLES), i, key;
    for (i=0; i<keys.length; i++) {
        key = keys[i];
        this[key] = STYLES[key].canvas;
    }
};

/**
 * Applies styles on restore
 * @param styleState
 * @private
 */
ctx.prototype.__applyStyleState = function (styleState) {
    var keys = Object.keys(styleState), i, key;
    for (i=0; i<keys.length; i++) {
        key = keys[i];
        this[key] = styleState[key];
    }
};

/**
 * Gets the current style state
 * @return {Object}
 * @private
 */
ctx.prototype.__getStyleState = function () {
    var i, styleState = {}, keys = Object.keys(STYLES), key;
    for (i=0; i<keys.length; i++) {
        key = keys[i];
        styleState[key] = this[key];
    }
    return styleState;
};

/**
 * Apples the current styles to the current SVG element. On "ctx.fill" or "ctx.stroke"
 * @param type
 * @private
 */
ctx.prototype.__applyStyleToCurrentElement = function (type) {
    var currentElement = this.__currentElement;
    var currentStyleGroup = this.__currentElementsToStyle;
    if (currentStyleGroup) {
        currentElement.setAttribute(type, "");
        currentElement = currentStyleGroup.element;
        currentStyleGroup.children.forEach(function (node) {
            node.setAttribute(type, "");
        })
    }

    var keys = Object.keys(STYLES), i, style, value, id, regex, matches;
    for (i = 0; i < keys.length; i++) {
        style = STYLES[keys[i]];
        value = this[keys[i]];
        if (style.apply) {
            //is this a gradient or pattern?
            if (value instanceof CanvasPattern) {
                //pattern
                if (value.__ctx) {
                    //copy over defs
                    while(value.__ctx.__defs.childNodes.length) {
                        id = value.__ctx.__defs.childNodes[0].getAttribute("id");
                        this.__ids[id] = id;
                        this.__defs.appendChild(value.__ctx.__defs.childNodes[0]);
                    }
                }
                currentElement.setAttribute(style.apply, format("url(#{id})", {id:value.__root.getAttribute("id")}));
            }
            else if (value instanceof CanvasGradient) {
                //gradient
                currentElement.setAttribute(style.apply, format("url(#{id})", {id:value.__root.getAttribute("id")}));
            } else if (style.apply.indexOf(type)!==-1 && style.svg !== value) {
                if ((style.svgAttr === "stroke" || style.svgAttr === "fill") && value.indexOf("rgba") !== -1) {
                    //separate alpha value, since illustrator can't handle it
                    regex = /rgba\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d?\.?\d*)\s*\)/gi;
                    matches = regex.exec(value);
                    currentElement.setAttribute(style.svgAttr, format("rgb({r},{g},{b})", {r:matches[1], g:matches[2], b:matches[3]}));
                    //should take globalAlpha here
                    var opacity = matches[4];
                    var globalAlpha = this.globalAlpha;
                    if (globalAlpha != null) {
                        opacity *= globalAlpha;
                    }
                    currentElement.setAttribute(style.svgAttr+"-opacity", opacity);
                } else {
                    var attr = style.svgAttr;
                    if (keys[i] === 'globalAlpha') {
                        attr = type+'-'+style.svgAttr;
                        if (currentElement.getAttribute(attr)) {
                                //fill-opacity or stroke-opacity has already been set by stroke or fill.
                            continue;
                        }
                    }
                    //otherwise only update attribute if right type, and not svg default
                    currentElement.setAttribute(attr, value);
                }
            }
        }
    }
};

/**
 * Will return the closest group or svg node. May return the current element.
 * @private
 */
ctx.prototype.__closestGroupOrSvg = function (node) {
    node = node || this.__currentElement;
    if (node.nodeName === "g" || node.nodeName === "svg") {
        return node;
    } else {
        return this.__closestGroupOrSvg(node.parentNode);
    }
};

/**
 * Returns the serialized value of the svg so far
 * @param fixNamedEntities - Standalone SVG doesn't support named entities, which document.createTextNode encodes.
 *                           If true, we attempt to find all named entities and encode it as a numeric entity.
 * @return serialized svg
 */
ctx.prototype.getSerializedSvg = function (fixNamedEntities) {
    var serialized = new XMLSerializer().serializeToString(this.__root),
        keys, i, key, value, regexp, xmlns;

    //IE search for a duplicate xmnls because they didn't implement setAttributeNS correctly
    xmlns = /xmlns="http:\/\/www\.w3\.org\/2000\/svg".+xmlns="http:\/\/www\.w3\.org\/2000\/svg/gi;
    if (xmlns.test(serialized)) {
        serialized = serialized.replace('xmlns="http://www.w3.org/2000/svg','xmlns:xlink="http://www.w3.org/1999/xlink');
    }

    if (fixNamedEntities) {
        keys = Object.keys(namedEntities);
        //loop over each named entity and replace with the proper equivalent.
        for (i=0; i<keys.length; i++) {
            key = keys[i];
            value = namedEntities[key];
            regexp = new RegExp(key, "gi");
            if (regexp.test(serialized)) {
                serialized = serialized.replace(regexp, value);
            }
        }
    }

    return serialized;
};


/**
 * Returns the root svg
 * @return svg
 */
ctx.prototype.getSvg = function () {
    return this.__root;
};
/**
 * Will generate a group tag.
 */
ctx.prototype.save = function () {
    var group = this.__createElement("g");
    var parent = this.__closestGroupOrSvg();
    this.__groupStack.push(parent);
    parent.appendChild(group);
    this.__currentElement = group;
    this.__stack.push(this.__getStyleState());
};
/**
 * Sets current element to parent, or just root if already root
 */
ctx.prototype.restore = function () {
    this.__currentElement = this.__groupStack.pop();
    this.__currentElementsToStyle = null;
    //Clearing canvas will make the poped group invalid, currentElement is set to the root group node.
    if (!this.__currentElement) {
        this.__currentElement = this.__root.childNodes[1];
    }
    var state = this.__stack.pop();
    this.__applyStyleState(state);
};

/**
 * Helper method to add transform
 * @private
 */
ctx.prototype.__addTransform = function (t) {
    //if the current element has siblings, add another group
    var parent = this.__closestGroupOrSvg();
    if (parent.childNodes.length > 0) {
        if (this.__currentElement.nodeName === "path") {
            if (!this.__currentElementsToStyle) this.__currentElementsToStyle = {element: parent, children: []};
            this.__currentElementsToStyle.children.push(this.__currentElement)
            this.__applyCurrentDefaultPath();
        }

        var group = this.__createElement("g");
        parent.appendChild(group);
        this.__currentElement = group;
    }

    var transform = this.__currentElement.getAttribute("transform");
    if (transform) {
        transform += " ";
    } else {
        transform = "";
    }
    transform += t;
    this.__currentElement.setAttribute("transform", transform);
};

/**
 *  scales the current element
 */
ctx.prototype.scale = function (x, y) {
    if (y === undefined) {
        y = x;
    }
    this.__addTransform(format("scale({x},{y})", {x:x, y:y}));
};

/**
 * rotates the current element
 */
ctx.prototype.rotate = function (angle) {
    var degrees = (angle * 180 / Math.PI);
    this.__addTransform(format("rotate({angle},{cx},{cy})", {angle:degrees, cx:0, cy:0}));
};

/**
 * translates the current element
 */
ctx.prototype.translate = function (x, y) {
    this.__addTransform(format("translate({x},{y})", {x:x,y:y}));
};

/**
 * applies a transform to the current element
 */
ctx.prototype.transform = function (a, b, c, d, e, f) {
    this.__addTransform(format("matrix({a},{b},{c},{d},{e},{f})", {a:a, b:b, c:c, d:d, e:e, f:f}));
};

/**
 * Create a new Path Element
 */
ctx.prototype.beginPath = function () {
    var path, parent;

    // Note that there is only one current default path, it is not part of the drawing state.
    // See also: https://html.spec.whatwg.org/multipage/scripting.html#current-default-path
    this.__currentDefaultPath = "";
    this.__currentPosition = {};

    path = this.__createElement("path", {}, true);
    parent = this.__closestGroupOrSvg();
    parent.appendChild(path);
    this.__currentElement = path;
};

/**
 * Helper function to apply currentDefaultPath to current path element
 * @private
 */
ctx.prototype.__applyCurrentDefaultPath = function () {
    var currentElement = this.__currentElement;
    if (currentElement.nodeName === "path") {
        currentElement.setAttribute("d", this.__currentDefaultPath);
    } else {
        console.error("Attempted to apply path command to node", currentElement.nodeName);
    }
};

/**
 * Helper function to add path command
 * @private
 */
ctx.prototype.__addPathCommand = function (command) {
    this.__currentDefaultPath += " ";
    this.__currentDefaultPath += command;
};

/**
 * Adds the move command to the current path element,
 * if the currentPathElement is not empty create a new path element
 */
ctx.prototype.moveTo = function (x,y) {
    if (this.__currentElement.nodeName !== "path") {
        this.beginPath();
    }

    // creates a new subpath with the given point
    this.__currentPosition = {x: x, y: y};
    this.__addPathCommand(format("M {x} {y}", {x:x, y:y}));
};

/**
 * Closes the current path
 */
ctx.prototype.closePath = function () {
    if (this.__currentDefaultPath) {
        this.__addPathCommand("Z");
    }
};

/**
 * Adds a line to command
 */
ctx.prototype.lineTo = function (x, y) {
    this.__currentPosition = {x: x, y: y};
    if (this.__currentDefaultPath.indexOf('M') > -1) {
        this.__addPathCommand(format("L {x} {y}", {x:x, y:y}));
    } else {
        this.__addPathCommand(format("M {x} {y}", {x:x, y:y}));
    }
};

/**
 * Add a bezier command
 */
ctx.prototype.bezierCurveTo = function (cp1x, cp1y, cp2x, cp2y, x, y) {
    this.__currentPosition = {x: x, y: y};
    this.__addPathCommand(format("C {cp1x} {cp1y} {cp2x} {cp2y} {x} {y}",
        {cp1x:cp1x, cp1y:cp1y, cp2x:cp2x, cp2y:cp2y, x:x, y:y}));
};

/**
 * Adds a quadratic curve to command
 */
ctx.prototype.quadraticCurveTo = function (cpx, cpy, x, y) {
    this.__currentPosition = {x: x, y: y};
    this.__addPathCommand(format("Q {cpx} {cpy} {x} {y}", {cpx:cpx, cpy:cpy, x:x, y:y}));
};


/**
 * Return a new normalized vector of given vector
 */
var normalize = function (vector) {
    var len = Math.sqrt(vector[0] * vector[0] + vector[1] * vector[1]);
    return [vector[0] / len, vector[1] / len];
};

/**
 * Adds the arcTo to the current path
 *
 * @see http://www.w3.org/TR/2015/WD-2dcontext-20150514/#dom-context-2d-arcto
 */
ctx.prototype.arcTo = function (x1, y1, x2, y2, radius) {
    // Let the point (x0, y0) be the last point in the subpath.
    var x0 = this.__currentPosition && this.__currentPosition.x;
    var y0 = this.__currentPosition && this.__currentPosition.y;

    // First ensure there is a subpath for (x1, y1).
    if (typeof x0 == "undefined" || typeof y0 == "undefined") {
        return;
    }

    // Negative values for radius must cause the implementation to throw an IndexSizeError exception.
    if (radius < 0) {
        throw new Error("IndexSizeError: The radius provided (" + radius + ") is negative.");
    }

    // If the point (x0, y0) is equal to the point (x1, y1),
    // or if the point (x1, y1) is equal to the point (x2, y2),
    // or if the radius radius is zero,
    // then the method must add the point (x1, y1) to the subpath,
    // and connect that point to the previous point (x0, y0) by a straight line.
    if (((x0 === x1) && (y0 === y1))
        || ((x1 === x2) && (y1 === y2))
        || (radius === 0)) {
        this.lineTo(x1, y1);
        return;
    }

    // Otherwise, if the points (x0, y0), (x1, y1), and (x2, y2) all lie on a single straight line,
    // then the method must add the point (x1, y1) to the subpath,
    // and connect that point to the previous point (x0, y0) by a straight line.
    var unit_vec_p1_p0 = normalize([x0 - x1, y0 - y1]);
    var unit_vec_p1_p2 = normalize([x2 - x1, y2 - y1]);
    if (unit_vec_p1_p0[0] * unit_vec_p1_p2[1] === unit_vec_p1_p0[1] * unit_vec_p1_p2[0]) {
        this.lineTo(x1, y1);
        return;
    }

    // Otherwise, let The Arc be the shortest arc given by circumference of the circle that has radius radius,
    // and that has one point tangent to the half-infinite line that crosses the point (x0, y0) and ends at the point (x1, y1),
    // and that has a different point tangent to the half-infinite line that ends at the point (x1, y1), and crosses the point (x2, y2).
    // The points at which this circle touches these two lines are called the start and end tangent points respectively.

    // note that both vectors are unit vectors, so the length is 1
    var cos = (unit_vec_p1_p0[0] * unit_vec_p1_p2[0] + unit_vec_p1_p0[1] * unit_vec_p1_p2[1]);
    var theta = Math.acos(Math.abs(cos));

    // Calculate origin
    var unit_vec_p1_origin = normalize([
        unit_vec_p1_p0[0] + unit_vec_p1_p2[0],
        unit_vec_p1_p0[1] + unit_vec_p1_p2[1]
    ]);
    var len_p1_origin = radius / Math.sin(theta / 2);
    var x = x1 + len_p1_origin * unit_vec_p1_origin[0];
    var y = y1 + len_p1_origin * unit_vec_p1_origin[1];

    // Calculate start angle and end angle
    // rotate 90deg clockwise (note that y axis points to its down)
    var unit_vec_origin_start_tangent = [
        -unit_vec_p1_p0[1],
        unit_vec_p1_p0[0]
    ];
    // rotate 90deg counter clockwise (note that y axis points to its down)
    var unit_vec_origin_end_tangent = [
        unit_vec_p1_p2[1],
        -unit_vec_p1_p2[0]
    ];
    var getAngle = function (vector) {
        // get angle (clockwise) between vector and (1, 0)
        var x = vector[0];
        var y = vector[1];
        if (y >= 0) { // note that y axis points to its down
            return Math.acos(x);
        } else {
            return -Math.acos(x);
        }
    };
    var startAngle = getAngle(unit_vec_origin_start_tangent);
    var endAngle = getAngle(unit_vec_origin_end_tangent);

    // Connect the point (x0, y0) to the start tangent point by a straight line
    this.lineTo(x + unit_vec_origin_start_tangent[0] * radius,
                y + unit_vec_origin_start_tangent[1] * radius);

    // Connect the start tangent point to the end tangent point by arc
    // and adding the end tangent point to the subpath.
    this.arc(x, y, radius, startAngle, endAngle);
};

/**
 * Sets the stroke property on the current element
 */
ctx.prototype.stroke = function () {
    if (this.__currentElement.nodeName === "path") {
        this.__currentElement.setAttribute("paint-order", "fill stroke markers");
    }
    this.__applyCurrentDefaultPath();
    this.__applyStyleToCurrentElement("stroke");
};

/**
 * Sets fill properties on the current element
 */
ctx.prototype.fill = function () {
    if (this.__currentElement.nodeName === "path") {
        this.__currentElement.setAttribute("paint-order", "stroke fill markers");
    }
    this.__applyCurrentDefaultPath();
    this.__applyStyleToCurrentElement("fill");
};

/**
 *  Adds a rectangle to the path.
 */
ctx.prototype.rect = function (x, y, width, height) {
    if (this.__currentElement.nodeName !== "path") {
        this.beginPath();
    }
    this.moveTo(x, y);
    this.lineTo(x+width, y);
    this.lineTo(x+width, y+height);
    this.lineTo(x, y+height);
    this.lineTo(x, y);
    this.closePath();
};


/**
 * adds a rectangle element
 */
ctx.prototype.fillRect = function (x, y, width, height) {
    var rect, parent;
    rect = this.__createElement("rect", {
        x : x,
        y : y,
        width : width,
        height : height
    }, true);
    parent = this.__closestGroupOrSvg();
    parent.appendChild(rect);
    this.__currentElement = rect;
    this.__applyStyleToCurrentElement("fill");
};

/**
 * Draws a rectangle with no fill
 * @param x
 * @param y
 * @param width
 * @param height
 */
ctx.prototype.strokeRect = function (x, y, width, height) {
    var rect, parent;
    rect = this.__createElement("rect", {
        x : x,
        y : y,
        width : width,
        height : height
    }, true);
    parent = this.__closestGroupOrSvg();
    parent.appendChild(rect);
    this.__currentElement = rect;
    this.__applyStyleToCurrentElement("stroke");
};


/**
 * Clear entire canvas:
 * 1. save current transforms
 * 2. remove all the childNodes of the root g element
 */
ctx.prototype.__clearCanvas = function () {
    var current = this.__closestGroupOrSvg(),
        transform = current.getAttribute("transform");
    var rootGroup = this.__root.childNodes[1];
    var childNodes = rootGroup.childNodes;
    for (var i = childNodes.length - 1; i >= 0; i--) {
        if (childNodes[i]) {
            rootGroup.removeChild(childNodes[i]);
        }
    }
    this.__currentElement = rootGroup;
    //reset __groupStack as all the child group nodes are all removed.
    this.__groupStack = [];
    if (transform) {
        this.__addTransform(transform);
    }
};

/**
 * "Clears" a canvas by just drawing a white rectangle in the current group.
 */
ctx.prototype.clearRect = function (x, y, width, height) {
    //clear entire canvas
    if (x === 0 && y === 0 && width === this.width && height === this.height) {
        this.__clearCanvas();
        return;
    }
    var rect, parent = this.__closestGroupOrSvg();
    rect = this.__createElement("rect", {
        x : x,
        y : y,
        width : width,
        height : height,
        fill : "#FFFFFF"
    }, true);
    parent.appendChild(rect);
};

/**
 * Adds a linear gradient to a defs tag.
 * Returns a canvas gradient object that has a reference to it's parent def
 */
ctx.prototype.createLinearGradient = function (x1, y1, x2, y2) {
    var grad = this.__createElement("linearGradient", {
        id : randomString(this.__ids),
        x1 : x1+"px",
        x2 : x2+"px",
        y1 : y1+"px",
        y2 : y2+"px",
        "gradientUnits" : "userSpaceOnUse"
    }, false);
    this.__defs.appendChild(grad);
    return new CanvasGradient(grad, this);
};

/**
 * Adds a radial gradient to a defs tag.
 * Returns a canvas gradient object that has a reference to it's parent def
 */
ctx.prototype.createRadialGradient = function (x0, y0, r0, x1, y1, r1) {
    var grad = this.__createElement("radialGradient", {
        id : randomString(this.__ids),
        cx : x1+"px",
        cy : y1+"px",
        r  : r1+"px",
        fx : x0+"px",
        fy : y0+"px",
        "gradientUnits" : "userSpaceOnUse"
    }, false);
    this.__defs.appendChild(grad);
    return new CanvasGradient(grad, this);

};

/**
 * Parses the font string and returns svg mapping
 * @private
 */
ctx.prototype.__parseFont = function () {
    var regex = /^\s*(?=(?:(?:[-a-z]+\s*){0,2}(italic|oblique))?)(?=(?:(?:[-a-z]+\s*){0,2}(small-caps))?)(?=(?:(?:[-a-z]+\s*){0,2}(bold(?:er)?|lighter|[1-9]00))?)(?:(?:normal|\1|\2|\3)\s*){0,3}((?:xx?-)?(?:small|large)|medium|smaller|larger|[.\d]+(?:\%|in|[cem]m|ex|p[ctx]))(?:\s*\/\s*(normal|[.\d]+(?:\%|in|[cem]m|ex|p[ctx])))?\s*([-,\'\"\sa-z0-9]+?)\s*$/i;
    var fontPart = regex.exec( this.font );
    var data = {
        style : fontPart[1] || 'normal',
        size : fontPart[4] || '10px',
        family : fontPart[6] || 'sans-serif',
        weight: fontPart[3] || 'normal',
        decoration : fontPart[2] || 'normal',
        href : null
    };

    //canvas doesn't support underline natively, but we can pass this attribute
    if (this.__fontUnderline === "underline") {
        data.decoration = "underline";
    }

    //canvas also doesn't support linking, but we can pass this as well
    if (this.__fontHref) {
        data.href = this.__fontHref;
    }

    return data;
};

/**
 * Helper to link text fragments
 * @param font
 * @param element
 * @return {*}
 * @private
 */
ctx.prototype.__wrapTextLink = function (font, element) {
    if (font.href) {
        var a = this.__createElement("a");
        a.setAttributeNS("http://www.w3.org/1999/xlink", "xlink:href", font.href);
        a.appendChild(element);
        return a;
    }
    return element;
};

/**
 * Fills or strokes text
 * @param text
 * @param x
 * @param y
 * @param action - stroke or fill
 * @private
 */
ctx.prototype.__applyText = function (text, x, y, action) {
    var font = this.__parseFont(),
        parent = this.__closestGroupOrSvg(),
        textElement = this.__createElement("text", {
            "font-family" : font.family,
            "font-size" : font.size,
            "font-style" : font.style,
            "font-weight" : font.weight,
            "text-decoration" : font.decoration,
            "x" : x,
            "y" : y,
            "text-anchor": getTextAnchor(this.textAlign),
            "dominant-baseline": getDominantBaseline(this.textBaseline)
        }, true);

    textElement.appendChild(this.__document.createTextNode(text));
    this.__currentElement = textElement;
    this.__applyStyleToCurrentElement(action);
    parent.appendChild(this.__wrapTextLink(font,textElement));
};

/**
 * Creates a text element
 * @param text
 * @param x
 * @param y
 */
ctx.prototype.fillText = function (text, x, y) {
    this.__applyText(text, x, y, "fill");
};

/**
 * Strokes text
 * @param text
 * @param x
 * @param y
 */
ctx.prototype.strokeText = function (text, x, y) {
    this.__applyText(text, x, y, "stroke");
};

/**
 * No need to implement this for svg.
 * @param text
 * @return {TextMetrics}
 */
ctx.prototype.measureText = function (text) {
    this.__ctx.font = this.font;
    return this.__ctx.measureText(text);
};

/**
 *  Arc command!
 */
ctx.prototype.arc = function (x, y, radius, startAngle, endAngle, counterClockwise) {
    // in canvas no circle is drawn if no angle is provided.
    if (startAngle === endAngle) {
        return;
    }
    startAngle = startAngle % (2*Math.PI);
    endAngle = endAngle % (2*Math.PI);
    if (startAngle === endAngle) {
        //circle time! subtract some of the angle so svg is happy (svg elliptical arc can't draw a full circle)
        endAngle = ((endAngle + (2*Math.PI)) - 0.001 * (counterClockwise ? -1 : 1)) % (2*Math.PI);
    }
    var endX = x+radius*Math.cos(endAngle),
        endY = y+radius*Math.sin(endAngle),
        startX = x+radius*Math.cos(startAngle),
        startY = y+radius*Math.sin(startAngle),
        sweepFlag = counterClockwise ? 0 : 1,
        largeArcFlag = 0,
        diff = endAngle - startAngle;

    // https://github.com/gliffy/canvas2svg/issues/4
    if (diff < 0) {
        diff += 2*Math.PI;
    }

    if (counterClockwise) {
        largeArcFlag = diff > Math.PI ? 0 : 1;
    } else {
        largeArcFlag = diff > Math.PI ? 1 : 0;
    }

    this.lineTo(startX, startY);
    this.__addPathCommand(format("A {rx} {ry} {xAxisRotation} {largeArcFlag} {sweepFlag} {endX} {endY}",
        {rx:radius, ry:radius, xAxisRotation:0, largeArcFlag:largeArcFlag, sweepFlag:sweepFlag, endX:endX, endY:endY}));

    this.__currentPosition = {x: endX, y: endY};
};

/**
 * Generates a ClipPath from the clip command.
 */
ctx.prototype.clip = function () {
    var group = this.__closestGroupOrSvg(),
        clipPath = this.__createElement("clipPath"),
        id =  randomString(this.__ids),
        newGroup = this.__createElement("g");

    this.__applyCurrentDefaultPath();
    group.removeChild(this.__currentElement);
    clipPath.setAttribute("id", id);
    clipPath.appendChild(this.__currentElement);

    this.__defs.appendChild(clipPath);

    //set the clip path to this group
    group.setAttribute("clip-path", format("url(#{id})", {id:id}));

    //clip paths can be scaled and transformed, we need to add another wrapper group to avoid later transformations
    // to this path
    group.appendChild(newGroup);

    this.__currentElement = newGroup;

};

/**
 * Draws a canvas, image or mock context to this canvas.
 * Note that all svg dom manipulation uses node.childNodes rather than node.children for IE support.
 * http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-drawimage
 */
ctx.prototype.drawImage = function () {
    //convert arguments to a real array
    var args = Array.prototype.slice.call(arguments),
        image=args[0],
        dx, dy, dw, dh, sx=0, sy=0, sw, sh, parent, svg, defs, group,
        currentElement, svgImage, canvas, context, id;

    if (args.length === 3) {
        dx = args[1];
        dy = args[2];
        sw = image.width;
        sh = image.height;
        dw = sw;
        dh = sh;
    } else if (args.length === 5) {
        dx = args[1];
        dy = args[2];
        dw = args[3];
        dh = args[4];
        sw = image.width;
        sh = image.height;
    } else if (args.length === 9) {
        sx = args[1];
        sy = args[2];
        sw = args[3];
        sh = args[4];
        dx = args[5];
        dy = args[6];
        dw = args[7];
        dh = args[8];
    } else {
        throw new Error("Inavlid number of arguments passed to drawImage: " + arguments.length);
    }

    parent = this.__closestGroupOrSvg();
    currentElement = this.__currentElement;
    var translateDirective = "translate(" + dx + ", " + dy + ")";
    if (image instanceof ctx) {
        //canvas2svg mock canvas context. In the future we may want to clone nodes instead.
        //also I'm currently ignoring dw, dh, sw, sh, sx, sy for a mock context.
        svg = image.getSvg().cloneNode(true);
        if (svg.childNodes && svg.childNodes.length > 1) {
            defs = svg.childNodes[0];
            while(defs.childNodes.length) {
                id = defs.childNodes[0].getAttribute("id");
                this.__ids[id] = id;
                this.__defs.appendChild(defs.childNodes[0]);
            }
            group = svg.childNodes[1];
            if (group) {
                //save original transform
                var originTransform = group.getAttribute("transform");
                var transformDirective;
                if (originTransform) {
                    transformDirective = originTransform+" "+translateDirective;
                } else {
                    transformDirective = translateDirective;
                }
                group.setAttribute("transform", transformDirective);
                parent.appendChild(group);
            }
        }
    } else if (image.nodeName === "CANVAS" || image.nodeName === "IMG") {
        //canvas or image
        svgImage = this.__createElement("image");
        svgImage.setAttribute("width", dw);
        svgImage.setAttribute("height", dh);
        svgImage.setAttribute("preserveAspectRatio", "none");

        if (sx || sy || sw !== image.width || sh !== image.height) {
            //crop the image using a temporary canvas
            canvas = this.__document.createElement("canvas");
            canvas.width = dw;
            canvas.height = dh;
            context = canvas.getContext("2d");
            context.drawImage(image, sx, sy, sw, sh, 0, 0, dw, dh);
            image = canvas;
        }
        svgImage.setAttribute("transform", translateDirective);
        svgImage.setAttributeNS("http://www.w3.org/1999/xlink", "xlink:href",
            image.nodeName === "CANVAS" ? image.toDataURL() : image.getAttribute("src"));
        parent.appendChild(svgImage);
    }
};

/**
 * Generates a pattern tag
 */
ctx.prototype.createPattern = function (image, repetition) {
    var pattern = this.__document.createElementNS("http://www.w3.org/2000/svg", "pattern"), id = randomString(this.__ids),
        img;
    pattern.setAttribute("id", id);
    pattern.setAttribute("width", image.width);
    pattern.setAttribute("height", image.height);
    if (image.nodeName === "CANVAS" || image.nodeName === "IMG") {
        img = this.__document.createElementNS("http://www.w3.org/2000/svg", "image");
        img.setAttribute("width", image.width);
        img.setAttribute("height", image.height);
        img.setAttributeNS("http://www.w3.org/1999/xlink", "xlink:href",
            image.nodeName === "CANVAS" ? image.toDataURL() : image.getAttribute("src"));
        pattern.appendChild(img);
        this.__defs.appendChild(pattern);
    } else if (image instanceof ctx) {
        pattern.appendChild(image.__root.childNodes[1]);
        this.__defs.appendChild(pattern);
    }
    return new CanvasPattern(pattern, this);
};

ctx.prototype.setLineDash = function (dashArray) {
    if (dashArray && dashArray.length > 0) {
        this.lineDash = dashArray.join(",");
    } else {
        this.lineDash = null;
    }
};

/**
 * Not yet implemented
 */
ctx.prototype.drawFocusRing = function () {};
ctx.prototype.createImageData = function () {};
ctx.prototype.getImageData = function () {};
ctx.prototype.putImageData = function () {};
ctx.prototype.globalCompositeOperation = function () {};
ctx.prototype.setTransform = function () {};

//add options for alternative namespace
// if (typeof window === "object") {
//     window.C2S = ctx;
// }

// CommonJS/Browserify
// if (typeof module === "object" && typeof module.exports === "object") {
//     module.exports = ctx;
// }

export default ctx;